Chair lift mechanism



ca. H. MARTIN CHAIR LIFT MECHANISM March 7, 1967 2 Sheets-Sheet 1 Filed Deb. so, 1964 IN V EN TOR.

Marfih 1967 G. H. MARTIN 3,307,820

' CHAIR LIFT MECHANISM Fi1ed Dec. 30, 1964 2 Sheets-Sheet 2 34 IN VEN TOR.

660/?66 M M4977 d2 W/, S5/%, 44 43 44 gag Q United States Patent 3,307,820 CHAIR LIFT MECHANISM George H. Martin, Chagrin Falls, Ohio, assignor to The Martin Brothers Electric Company, Cleveland, Ohio, a corporation of Ohio Filed Dec. 30, 1964, Ser. No. 422,308 8 Claims. (Cl. 248-410) This invention relates to a mechanism for lifting and lowering a load and, particularly, to a lifting and lowering mechanism for use in an adjustable-height chair of the type used in beauty salons and barber shops, for example.

Chairs which can be raised and lowered, as well as rotated, have 'been in use for many years. Commonly, it is necessary and/or desirable to be able to move such a chair up or down, as well as turn it around, with respect to its base, all while it is occupied or supporting a load. This invention is directed to a new and improved means for raising and lowering a load as, for example, a chair and its occupant. As will be understood from the following description, the apparatus disclosed and claimed herein is not limited to raising and lowering chairs and their occupants but may be employed as well in raising and lowering other loads through limited distances.

The primary object of this invention is to provide a simple, efficient mechanical means for raising and lowering a load. A further object is to provide such an apparatus having but a single operating and controlling ele ment or lever through which all the power necessary to operate and control the apparatus through all of its functions may be conveniently applied. Yet another object is to provide a simple and effective hydraulic means which cooperates with mechanical lifting and lowering apparatus to impede and cushion the lowering of the load without creating a like resistance to raising the load. Such hydraulic cushioning means is entirely automatic. A further object of this invention is to provide a lifting and lowering apparatus which is able to position a load accurately and repeatedly at any position throughout a range of positions. According to the inventions objects, this feature of the apparatus is to be accomplished solely with mechanical means. Yet another object of this invention is to provide means for rotating said lifting and lowering apparatus about a generally vertical axis. Still another object is to provide such means which includes means to stop and lock the apparatus in any position of rotation by operation of the single operating and control lever.

Briefly, this invention consists of a generally vertically arranged, two-part telescoping leg element that is able to be extended and retracted. A fixed tube is mounted on and supported by a base. A telescoping movable tube carries means, such as a chair, for accommodating a load. The movable tube part of the extensible and retract-able leg element is encircled by a pair of loose-fitting rings. The upper ring is pivotally connected to the base for up and down swinging movement about a horizontal axis spaced laterally from the leg element. The lower ring is pivotally connected to operating linkage which moves back and forth causing the lower ring to be moved up and down. The lower ring also has up and down swinging movement about its horizontal axis of pivot-a1 connection with the operating linkage.

Gravity tends to swing both rings downward about their horizontal axes of pivotal connection so that they are canted with respect to the extensible and retractable leg element and tend to :bind or grip it on opposite sides. The gripping action of the upper ring holds or locks the leg element against downward telescoping movement. The gripping of the lower ring tends to carry it and the operating linkage to which it is pivotally connected up or down with the leg element. Both rings have a position in their swinging movement which provides for free passage of the leg element through them.

The lifting and lowering of the leg element and the load mounted thereon is accomplished through the operating linkage by lifting the pivotally connected side of the lower or lifting ring while it surrounds the leg element at a point spaced well below the upper or locking ring so that it grippingly engages opposite sides of the leg element. Upward movement of the reciprocating linkage then lifts the lower ring and the leg element held by it up to a point where the lower ring approaches the upper ring. During this lift, the leg element, of course, slips upwardly and freely through the locking ring.

The lifting ring may then be lowered by the operating linkage to take a new bite on the leg element at a new position spaced below the locking ring. During this downward return stroke of the lifting ring, the leg element is held and its downward movement prevented by the canting or tipping of the locking ring about the horizontal axis of its pivotal connection with the base portion.

Such tipping is automatic, being started by gravity acting on the ring and further energized by the load on the leg element. The force of gravity may be augmented by resilient means tending to urge downwardly that side of the upper locking ring opposite the axis of its swinging motion. The leg element may be lifted to any position permitted by its telescoping length by alternately raising and lowering the lower or lifting ring as described above.

The leg element and its load may be lowered by and through the same operating linkage employed for lifting. For lowering, the operating linkage is moved upwardly, raising the lifting ring up to and into engagement with the locking ring so that both rings are, by virtue of the pivotal connection of the upper locking ring to the base portion and a force applied from beneath to and through the lower lifting ring by the operating linkage, moved to corresponding and generally parallel positions out of gripping engagement with the opposite sides of the leg element and permitting its free passage through both of the rings. A simple and effective hydraulic cushioning device cooperates to cushion and impede the downward movement of the leg element when released by both of the rings.

Further details of the invention and other of its features and advantages will be apparent from the following description of a preferred embodiment of it taken together with the accompanying drawings in which:

FIGURE 1 is a perspective elevation view of a chair positioned atop a base such as is employed with the'lifting and lowering apparatus of this invention;

FIGURE 2 is a partially sectioned side elevation of the base portion of the chair shown in FIGURE 1, showing the apparatus in one of its operating positions;

FIGURE 3 is an enlarged full cross-sectional elevation view of the base portion of the chair shown in FIGURE 1, showing the lifting and lowering apparatus contained therein in another of its operating positions;

FIGURE 4 is an enlarged detail view in perspective of certain of the operating elements of the apparatus seen in elevation in FIGURES 2 and 3;

FIGURE 5 is a transverse section view taken in the plane of line 55 in FIGURE 2; and

FIGURE 6 is an enlarged perspective view showing details of the rotational lock feature.

In the accompanying drawings and in the following description, a lifting and lowering apparatus comprehended by this invention is shown and described in the environment of a so-called styling chair such as is used in a barber shop or a beauty salon such as shown in FIGURE 1. The apparatus includes a flaring circular lower base portion 10 surmounted by an upper base portion 11 arranged to rotate about a vertical axis. A chair, indicated generally at 12 and having a back rest 14, arms 15 and a seat 16, is supported by the apparatus embodying this invention. In FIGURE 1, an operating handle 17 projects outwardly from upper base portion 11 to which it is pivotally connected by a generally horizontal shaft or pin 18.

FIGURES 2 and 3 show details of the lifting, lowering and rotating apparatus inside upper and lower base portions 11 and 10. In these figures, chair 12 is not shown. Lower base portion has a generally circular, flaring bell shape, terminating at its upper and smaller-diameter end in a circular opening surrounded by an annular horizontal flange 19 provided with a downwardly depressed circular raceway 20. Upper base portion 11 has the general shape of a truncated core or flower pot placed upside down on the lower base portion 10. Annular flange 21, having a circular raceway 22 therein and corresponding to annular flange 19 and its raceway 20, lies in a generally horizontal plane attached to the lower circular edge portion 23 of upper base portion 11 by suitable means such as bolts 24. Flanges 19 and 21 are held apart and permitted to rotate relative to each other by a number of ball bearings 25, placed and held between cooperating raceways 20 and 22. The lower and upper base portions 10 and 11 are held together, though permitted relative rotational movement with respect to each other by a circular retaining lip 26 attached to upper flange 21 as by bolts 27. Lip 26 extends radially beneath and overlaps the inward extent of lower flange 19. A thin annular plastic washer 28 lies between flange 19 and lip 26, particularly in the area of their overlap. Normally, lip 26 has only smooth and quiet sliding engagement with flange 19. However, pressing retaining lip 26 and flange 19, together, will increase the friction between them and tend to prevent or arrest relative rotational movement between the lower and upper base portions 10 and 11. A means for accomplishing this is described below.

A telescoping leg element, indicated generally at 36, stands generally vertically in the center of lower and upper base portions 10 and 11 and extends outwardly through the top of the latter. As shown most clearly in FIGURE 3, leg element 30 consists of a fixed cylindrical tube 32, supported vertically by a number of vertical rods 33 spaced around the outside of tube 32 and extending vertically between the upper end wall 31 of upper base portion 11 and bottom flange 34 extending radially outwardly from the lower end of tube 32. Rods 33 may be provided with threaded ends for turning into tapped holes and/or nuts.

A sliding cylindrical tube 36 telescopes over fixed tube 32. The lower end of tube 36 is free to telescope all the way down to bottom flange 34 at the lower end of fixed tube 32. Sliding tube 36 can telescope upwardly through a central opening in upper end wall 31 of upper base portion 11. Cooperating fixed tube 32 and sliding tube 36 provide a smoothly guided, extensible and retractable leg element, supported by the base portion and able to extend and retract along a generally vertical longitudinal axis. Relative rotation of tubes 32 and 36 is prevented by the cooperating engagement of supporting rods 33 and annular guide flange 35 fixed to the lower end of sliding tube 36. Tubes 32 and 36, of course, can be rotated together and with upper base portion 11 relative to lower base portion 10 or ball bearings 25. The upper end of sliding tube 36 is provided with an appropriate fitting 37 for attachment to the seat of the chair.

The lower end of fixed tube 32 is closed by bottom flange 34 .and contains a fluid such as oil as indicated in FIGURE 3. The upper end of fixed tube 32 is provided with a pair of conventional neoprene seals 38 held in place by snap rings 39.

A piston rod 40, attached at one end to the upper end of sliding tube 36 extends axially down into the center of fixed tube 32 through and in sealing engagement with seals 38. Piston rod 40 is approximately equal in length with tubes 32 and 36 and approaches bottom flange 34 when the two tubes are fully telescoped as shown in FIG- 4 URE 3. A cup 41 is fastened to the lower end of rod 40 in a downwardly facing position between washers 42 by nut 43 turned on the end of rod 40. Preferably, the entire cup 41, and particularly the generally cylindrical side wall 44, is formed of a flexible, resilient material.

In its unstressed or unloaded state, as shown in FIG- URE 3, the cup preferably has a small clearance of, for example, about .020 inch with the interior surface of fixed tube 32. During upward motion of the cup through the fluid, cup wall 44 tends to deflect and be compressed inwardly, increasing its clearance with the tube walls. Thus, when sliding tube 36 telescopes upwardly and rod 40 and cup 41 are pulled through the fluid within fixed tube 32, fluid passes rather freely from the upper side of the cup to the lower side between the flexible side wall 44 of the cup and tube 32. When sliding tube 36 is lowered and rod 40 and cup 41 lowered with it through the fluid and fixed tube 32, flexible or bendable cup wall 44 is urged outwardly toward the interior surface of fixed tube 32, decreasing the clearance therebetween and impeding and cushioning the downward movement of the cup, rod and sliding tube. The slight resistance to upward motion provided by piston rod 40 and cup 41 tends to smooth out any abrupt or jerky movements of the leg element during an upward extension without unduly impeding the motion. During lowering or retraction of the leg element, the piston rod-mounted cup 41 in the fluid provides substantial impedance to motion and a smoothing and a cushioning effect.

The mechanism for lifting and holding sliding tube 36 at elevated positions of extension with respect to the base of the apparatus generally employs the principles of a well-known type of apparatus commonly referred to as a clutch collar or ring. Such a ring operates to grip a pipe or some longitudinal member passing through it and having an outside diameter or dimension at least slightly less than a corresponding inside diameter or dimension of the collar. When the ring is supported on one side only and permitted to cant or tip, the clutch collar or ring grippingly engages opposite sides of the pipe. While the broad principle involved is old and well known, the details and manner of its application and the resulting structure and its operation, as illustrated in the preferred embodiment described herein, are novel.

As shown in both FIGURES 2 and 3, an upper locking ring 45 and a lower lifting ring 46 surround and encircle sliding tube 36. Generally speaking, rings 45 and 46 loosely fit tube 3 6 when positioned generally in a plane normal to the longitudinal axis of leg element 30, as shown for example in FIGURE 3, allowing tube 36 to slide relatively freely through them. The interior walls of the passages orv bores through rings 45 and 4-6 through which tube 36 passes are preferably formed in a particular manner as shown in FIGURE 3 and described in greater detail below. Upper locking ring 45 is provided with a pair of diametrically opposite, radially extending projections 47 and 48. Projection 47 is pivotally connected to upper base portion 11 by means of pin 49 so that ring 45 has up and down swinging motion about a horizontal axis laterally spaced from the longitudinal axis of leg element 30. Projection 48 from upper ring 45 supports one end of compression spring 50 standing between it and upper end wall 31 of upper base portion 11. Spring 50, at all times, tends to swing upper ring 45 downwardly about pin 49 as seen in FIGURE 3.

Lower lifting ring 46 is also provided with a pair of diametrically opposite radial projections 51 and 52. Projection 5=1 rests and rides on a roller 53 carried by crank pin 54 of an operating crankshaft indicated generally at 55 and shown in enlarged detail in FIGURE 4. Roller 53 is preferably provided with radial flanges 56 at its ends to guide projection 51 of lifting ring 46 in its rolling engagement with the roller. Pin 54 and roller 53 generally provide a horizontal axis or fulcrum laterally spaced at varying distances from the vertical longitudinal axis of leg element 30 and about which lifting ring 46 swings up and down. Lifting ring projection 52 is attached to one end of tension spring 57, the other end of which is hooked onto bottom flange 3 4 at the lower end of fixed tube 32. Spring 57, at all times, tends to pull one side of lifting ring 46 downwardly. It will be noted that lifting ring projection 51 extends radially outwardly to substantially the same radial extent as locking ring projection 47. Also, the pivotally connected or carried projections 47 and 51 and the spring-associated projections 48 and 52 on the two rings are preferably vertically aligned and on opposite sides of the rings. A compression spring 58, carried in oppositely disposed pockets in the upper and lower faces of lifting and locking ring projections 51 and 47, respectively, tends to hold these projections apart in a manner and for a purpose explained below.

Operating crankshaft 55 comprises two main shaft portions 59 and 60 and a pair of crank arms 61 and 62 attached to the adjacent spaced apart ends of main shafts 5 9 and 60, respectively. Crank pin 54 extends between and is supported and carried by the outer ends of cranks 61 and 62.

Main shaft portions 59 and 60 of operating means 55 extend outwardly through the side wall of upper base portion '11 as shown in FIGURE 1. Operating handle 17 is secured to the ends of the main shafts outside upper base portion 11 so that its up and down movement turns main shafts 59 and 60 and crankshaft 55 back and forth. Crank pin 54 and roller 53 are raised and lowered on and along an arcuate path through something less than 90 of angular movement but which includes substantial horizontal and vertical components of displacement. Resilient means, such as helical springs 65 attached at one end to crank pin 54 and at the other end to bottom flange 34 of telescoping leg element 30, may be provided to exert a force in addition to the force provided by compression spring 58 tending to rotate operating crankshaft 55 in a clockwise direction as the mechanism is viewed in FIG- URES 2 and 3. The apparatus works as well with only spring 58 providing the returning force.

The preferred structure for locking upper and lower base portions 11 and 10 against relative rotation comprises a friction brake. Preferably, two such devices are used and arranged to apply clamping pressure tending to hold the two base portions together at two different circumferentially spaced points. As shown in detail and in enlarged scale cross section in FIGURE 6, each brake device comprises a brake button 66 loosely carried in an opening in flange 21 attached to upper base portion '11. Brake button 66 passes through flange 21 and frictionally engages the upper side of flange 19 on lower base portion 10, pressing flange 19 downwardly and against retaining lip 26 and the annular plastic washer 28 lying between flange 19 and retaining lip 26. Each brake button 66 is located beneath and operatively associated with a camming collar 67 located on main shafts 59 and 60 between the crank arms and the outer bearings. ming collars 67 are generally cylindrical except for a flat side 68 as seen particularly in FIGURES 2, 3, and 4. As long as the flat side 68 of a camming collar 67 is facing generally toward the top of its associated brake button 66, the collar is out of engagement with the button and no pressure is applied, tending to hold the two base portions against relative rotation. Whenever operating crankshaft 55 is turned far enough to bring the cylindrical portion of camming collars 67 into pressing engagement with the tops of brake buttons 66, upper and lower base portions 11 and 10 are locked together by the increased frictional engagement between the buttons 66 captured in one of the two base portion parts and flange 19 of the other as well as the pressing of flange 1 9 against retaining lip 26.

In operation, the lifting and lowering functions, as well as the swivel locking function, are all accomplished by appropriate movement of a lifting bale or operating handle Cam- 17. In FIGURE 2, telescoping leg element is fully retracted into its lowermost position and the movable operating elements of the apparatus are shown in a position locking the upper and lower base portions 11 and 10 against relative rotation. In FIGURE 2, operating crankshaft 55 is shown at the counterclockwise limit of its effective angular displacement, its further rotation being prevented by the engagement of the outer ends of crank arms 61 and 62 and the inside of upper base housing =11. Braking buttons 66 are engaged and pressed downwardly by camming collars 67 so that each brake button 66 captured in its opening through flange 21 frictionally engages flange 19 as well as presses flange 19 and retaining lip 26 together.

Further, in FIGURE 2, locking ring is swung downwardly by gravity and compression spring about pivot pin 49 into a position of engagement with opposite sides of outer cylindrical tube 36. While telescoping leg element '30 is shown in its fully retracted position, the gripping engagement of outer cylindrical tube 36 by locking ring 45 as positioned in FIGURE 2 would prevent the retraction of telescoping leg element 30 if it were extended.

When operating crankshaft is moved to its swivel locking position as seen in FIGURE 2, lifting ring 46 assumes a tipped position of gripping engagement along outer cylindrical tube 36 in a position longitudinally spaced between locking ring 45 and roller 53. Lifting ring 46 slides down tube 36 to this position from a position above during rotation of crankshaft 55 in a clockwise direction as seen in the drawings and is held there through frictional engagement with cylindrical tube 36. Such engagement occurs when the force exerted by tension spring 57 pulling down on one side of ring 45 exceeds the force exerted by compression spring 58 acting downwardly on the opposite side of the ring. A fixed stop device, such as a wire hook engageable by projection 51 for tipping lifting ring 46 may be used to positively fix the distance lifting ring 46 drops away and is spaced from locking ring 45 when handle 17 is raised. Tension springs 65, if used, pull down on crank pin 54 of crankshaft 55 and tend to move operating crankshaft 55 down into its FIGURE 2 position. Springs rotate crankshaft 55 until camming collars 67 touch and begin to exert some small pressure on brake buttons 66. In order to fully engage brake button 66 and to lock the swivel, a further upward pull must be applied to operatinghandle 17. In order to unlock the swivel, a downward push on the operating handle 17 will rotate camming collars 67 out of pressing engagement with brake buttons 66.

In order to raise or extend telescoping leg element 30, operating handle 17 is depressed, bringing roller 53 into lifting engagement with the underside of lifting ring projection 51. Engagement between the roller and the lifting ring projection is made near the radially outward end of the projection and about vertically below pivot pin 49 holding locking ring 45. As operating handle 17 is depressed from that point at which roller 53 first engages lifting ring projection 51, crank pin 54 moves upwardly and radially inwardly so that roller 53 rolls along underneath locking ring projection 51 from its point of engagement near the outer end toward the base of the projection at the ring itself. It will be apparent that lifting ring 46 is thus caused to slide upwardly on outer cylindrical tube 36, compressing compression spring 58 and extending tension spring 65.

As lifting ring 46 slides upwardly, it engages the underside of locking ring 45. Suitable means, such as neo prene washer 69, may be provided between the engaging faces of rings 45 and 46 to cushion their engagement. An upwardly projecting lug on the upper side of lifting ring 46 provides positive direct engagement with the lower side of locking ring 45 when resilient washer 69 is slightly compressed.

Continued upward movement of lifting ring 46 causes locking ring 45 to swing upwardly about its pivot pin 49. At the same time, compression spring 58 between the two rings has been reduced and lifting ring 46 assumes an untipped position generally parallel to that of locking ring 45 and as shown in FIGURE 3.

In FIGURE 3, locking and lifting rings 45 and 46, respectively, are shown in partial section to reveal the relationship of the bore through the rings to outer cylindrical tube 36 and to show a preferred form of such bores. As shown in FIGURE 3, the two rings are in a position permitting passage of outer cylindrical tube 36 so that it is able to slide through them as a result of its own weight and/or the weight of any load it might be supporting. Thus, when operating handle 17 is fully depressed, roller 53 lifts and pushes both the rings together into a position of parallel alignment permitting telescoping leg element 30 to retract.

It will be noted that, as the operating mechanism approaches the free passage or lowering position shown in FIGURE 3, roller 53 radially approaches leg element 30 and presses upwardly on lifting ring 46 at a point radialy inwardly of pivot pin 49. This provides a mechanical advantage useful in urging the rings out of their tipped positions of gripping engagement in which they tend to be held by the weight of the telescoping parts of leg element 30 and any-thing they might support as well as the force of various springs. For example, as operating crankshaft 55 is rotated counterclockwise toward its position shown in FIGURE 3, the effective length of the lever arm between the axis of shafts 59 and 60 and the axis of pin 54 applying an upward force to the underside of lifting ring 46 and, thus, to ring 45, becomes shorter, increasing the mechanical advantage of forces applied in the usual manner to operating handle 17. A further advantage is gained by the fact, as the effective length of the lever arm of the force applied to the underside of rings 45 and 46 becomes shorter, the effective length of the lever arm between the point of application of force by operating crankshaft 55 and the axis of pivot pin 49 increases, providing an increase in the mechanical advantage of the force applied to the rings in opposition to the tipping forces applied to them by the various springs and the weight supported on the telescoping leg element 30.

As long as operating handle 17 is depressed to the position shown in FIGURE 3, cylindrical tube 36 of the telescoping leg element is free to retract. Also, as shown in FIGURE 3, brake buttons 66 are free of any engagement with camming collars 67, being substantially opposite their flat sides 68.

In order to extend and hold extended telescoping leg element 30, operating handle 17 is moved up and down between two positions that lie between the limiting positions shown in FIGURES 2 and 3. One of these positions is the position of rest of operating crankshaft 55 and consists of a position of rotation slightly counterclockwise from that shown in FIGURE 2 with brake button 66 released but with operating handle 17 held generally up by the downward pull of springs 65 on crank pin 54 and/ or the down push of compression spring 58. Through engagement of roller 53 and the ring, further depressionof operating handle 17 raises or lifts ring 46 and outer cylindrical tube 36 gripped by it.

As may be visualized in FIGURE 2, continued raising of lifting ring 46 in its tipped position of engagement moves it toward the underside of locking ring 45 and raises tube 36. During the lifting of ring 46 and the upward extension of tube 36, locking ring 45 tends to swing upwardly about pivot pin 49 a limited amount sufiicient to permit tube 36 to slide through it. The force tending to swing locking ring 45 is supplied through frictional engagement with moving cylindrical tube 36 and is sufficient to slightly compress spring 50 if necessary. When lifting ring 46 approaches and comes into contact with locking ring 45, a slight resistance to the continued counterclockwise motion of operating crankshaft 55 is encountered and is of an amount noticeable to one operat ing the device through operating handle 17 by hand or by foot. This additional resistance is due, in part at least, to the added force of spring 50 acting on the locking ring projection 48 which is encountered and must be overcome at this point in order to raise lifting ring 46 upwardly beyond its point of engagement with locking ring 45.

During normal lifting operations, depression of operating handle 17 is discontinued when this additional resistance is encountered and the handle is released or no longer pressed and is returned to its raised position by spring 58 and/ or spring 65. Telescoping cylindrical tube 36 no longer moves upwardly so that locking ring 45, under the urging of compression spring 50, tips whatever slight amount necessary into gripping engagement with tube 36 and holds and supports it in its recently elevated position. Under the influence of tension spring 57 and compression spring 58 and as permitted by the lowering of roller 53 as operating handle 17 is raised, lower lifting ring 46 slides downwardly in a relatively level position and out of gripping engagement with cylindrical tube 36 until compression spring 58 is fully extended and lifting ring 46 again tips into gripping engagement with cylindrical tube 36 under the dominating influence of tension spring 57.

As at the upper limit of lifting motion of operating crankshaft 55, a change in the forces provided primarily by the springs involved and detected in operating handle 17 indicates when lifting ring 46 is again in tipped gripping engagement with cylindrical outer tube 36 and the operator instinctively knows when to again depress operating handle 17 in order to extend tube 36 another hitch.

Each successive stroke of operating handle 17 raises or extends telescoping leg element 30 a distance approximately equal to the spacing between the oppositely dispose-d faces of locking and lifting rings 45 and 46, respectively, when in the position as shown in FIGURE 2. This position is determined primarily by the distance lifting ring 46 will slide down tube 36 under the influence of tension spring 57 and compression spring 58 before the ring tips into engagement with tube 36 and is thereby prevented from sliding further. This separation between the oppositely disposed bases of the rings in one successful form of this invention is approximately /8 of an inch.

The foregoing cycle of operation and stroking of operating handle 17 may be repeated as many times as necessary to extend or elevate telescoping leg element 30 to the desired position. From the operators standpoint, the elevating process comprises alternately and successively pressing down on operating handle 17 until increased resistance warns that lifting ring 46 has engaged locking ring 45 and removing the downward pressure from operating handle 17 so that it may swing upwardly by itself and lifting ring 46 may slide downwardly. When the operator desires to lower or retract telescoping leg element 3% from an extended or elevated position, operating handle 17 is depressed downwardly beyond the point of increased resistance encountered when the oppositely disposed faces of the rings are brought into engagement and until the rings are levelled or approximately parallelly aligned in their free passage position as shown in FIG- URE 3. As long as operating handle 17 is depressed sufficiently to hold the rings in this position, outer cylindrical tube 36 will retract at a rate dependent somewhat upon the weight of a load it might support and, mostly, by the passage of hydraulic fluid within fixed cylindrical tube 32 past the outwardly flexed side wall 44 of cup 41 as it passes downwardly together with cylindrical tube 36. Of course, the downward movement of telescoping leg ele ment 30 may be interrupted at any point before it reaches the lowermost limit of its travel by releasing operating handle 17, permitting lifting ring 46 to drop away from the underside of locking ring 45 so that the latter may 9 be urged into tipping engagement by compression spring 50.

The preferred form of the bore or passages through lifting and locking rings 46 and 45, respectively, is revealed in the sectioned portions of the rings in FIGURE 3 and in perspective in FIGURE 4. The bores in each of the rings are substantially the same. Each bore has diametrically opposite portions of its side wall laterally offset. Another pair of diametrically opposite portions of the bore of the side wall positioned between the offset portions are not offset. Such a bore may be conveniently formed by the combination of the pair of circular bores entering opposite faces of the ring and having parallel and laterally offset axes with the lateral offset aligned along the axis of the diametrically opposite projections on each of the rings. Further, the offset in the two circular bores is such that the upper portion is spaced laterally farther from the pivotally connected or supported end of the ring than is the lower portion of the bore. Such a bore formation provides good gripping engagement with the outside of telescoping tube 36.

It will be apparent from FIGURE 3 that the difference between the least dimension of the inside diameter of the rings 45 and 46 is the same as the inside diameter of the upper or the lower portion of the bores through the rings as seen in FIGURE 3. The diametrically opposite and laterally offset inside diameters of the rings tend to provide a self-energizing aspect to their gripping engagement of cylindrical tube 36 so that, as forces tending to retract leg element 30 by sliding tube 36 downward through the rings increase, the gripping engagement and holding power of either or both of the tipped rings to resist this tendency increases.

The particular bore design preferred and described above also permits the quick, clean release from gripping engagement of the rings with cylindrical tube 36. This is because the laterally offset and diametrically opposite engaging portions of the internal walls of the bores of the rings tend to be translated only outwardly and away from the walls of cylinder 36 with which they are frictionally engaged when the rings are swung from their tipped position of gripping engagement such as shown in FIGURE 2 to their free-passage position of parallel and generally level alignment as shown in FIGURE 3.

Whereas it may be more convenient to employ telescoping elements of circular cross section and generally circular rings having circular offset bores as described in the preferred embodiment, it will be apparent that other crosssectional shapes may also be employed to the same end and that this invention comprehends such other shapes and forms.

The essentially mechanical apparatus combined with the hydraulic cushioning means comprising a preferred embodiment of this invention provides an efficient, effective, and economical elevating and lowering apparatus, well adapted to be manually operated in a wide variety of applications, including those mentioned above, and fully comparable in operational feel and effectiveness to full hydraulic apparatus sometimes employed in such applicatlons.

Those skilled in the art will appreciate that various changes and modifications can be made in the apparatus described herein without departing from the spirit and scope of the invention.

I claim:

1. Apparatus for lifting and lowering a load comprising a base portion,

an extensible and retractable leg element having a generally vertically extending longitudinal axis and mounted on and supported by said base portion for extension and retraction along its said longitudinal axis,

a. locking ring encircling said leg element and pivotally connected along one side to said base portion for swinging movement about a generally horizontal axis,

the inside transverse dimensions of said locking ring being large enough to permit passage therethrough of said leg element when said ring swings to a freepassage position placing said transverse dimensions substantially in a plane normal to said longitudinal axis of said leg element and small enough to prevent passage therethrough of said leg element by gripping engagement on opposite sides thereof by adjacent portions of said ring when said ring swings away from a free-passage position,

a lifting ring encircling said leg element below said locking ring and having a loose tipping fit with said leg element, the inside transverse dimensions of said lifting ring being large enough to permit passage therethrough of said leg element when said ring tips to a free-passage position placing said transverse dimensions in a plane normal to said longitudinal axis of said leg element and small enough to prevent passage therethrough of said leg element by gripping engagement on opposite sides thereof by adjacent portions of said ring when said ring tips away from a free-passage position,

movable operating means supported by said base portion and comprising a tipping and lifting portion having an up and down component of motion adjacent to and extending along said leg element, said tipping and lifting portion having cooperating engagement with the side of said lifting ring generally vertically below the pivotally connected side of said locking ring and movable upwardly for tipping said lifting ring into gripping engagement with opposite sides of said leg element and for lifting said lifting ring so tipped and engaged and thereby extending said leg element upwardly and through said locking ring,

said movable operating means having a range of motion of sufficient extent while engaged with said lifting ring to raise said lifting ring to an upper lifted position of cooperating engagement with said lock ing ring, said tipping and lifting portion of said movable operating means having supportable engagement with said lifting ring radially inwardly of the horizontal axis of pivotal motion of said locking ring and said base for urging together and tipping both of said rings out of their tipped positions of gripping engagement into their free-passage positions permitting the downward passage of said leg element through both of said rings.

2. Apparatus according to claim 1 in which said leg element comprises a first longitudinally extending tube fixed to and supported by said base and a second longitudinally extending tube telescopingly engaging said first tube for longitudinal extension and retraction with respect thereto, and together with cushioning means comprising a rod fixed to the upper end of said second tube and extending downwardly therefrom inside both of said tubes,

'a flexible-walled cup fastened to the lower end of said rod with the open face of the cup facing downwardly and said walls stressed into light engagement with the interior walls of said first tube when stationary with respect thereto.

a fluid medium confined by and within said first tube and surrounding said rod and said cup,

whereby upward movement through said fluid of said rod and said cup attached thereto stresses said flexible ible walls of said cup into lighter than stationary engagement with the interior walls of said first tube and downward movement through said fluid of said rod and said cup attached thereto stresses said flexible walls of said cup into tighter than stationary engagement with the interior walls of said first tube.

3. Apparatus according to claim 1 in which said movable operating means comprises a main shaft mounted for rotation back and forth about an axis that is generally horizontal and passes beside said leg element, said rotating shaft providing said tipping and lifting portion of said movable operating means which has a back and forth component of motion toward and away from said leg element and extending generally radially from the axis thereof, said back and forth radial component of motion and said up and down axial component of motion of said tipping and lifting portion combining to move the point of cooperative engagement of said tipping and lifting portion and said lifting ring radially inwardly as said lifting ring is lifted by upward motion of said tipping and lifting portion.

4. Apparatus according to claim 3 in which said main shaft is structurally related to and fixedly mounted for rotation with respect to said pivotal connection with said locking ring so that the radial component of motion of said tipping and lifting portion of said movable operating means carries said point of engagement substantially radially inwardly of said pivotal connection of said locking ring and said base when said rings are brought into said cooperating engagement with each other by the upward axial component of motion of said tipping and lifting portion.

5. Apparatus according to claim 1 in which said movable operating means comprises a main shaft for rotation back and forth about an axis that is generally horizontal and passes beside said leg elements,

a crank extending outwardly from said shaft,

a crank pin attached to and supported by said crank at its outer end, said crank pin extending generally parallel to said shaft and comprising said tipping and lifting portion,

an operating handle attached to said shaft for turning said shaft back and forth and oscillating said crank to swing said crank pin along an arcuate path extending with respect to said leg element axially upwardly and radially inwardly in one direction and axially downwardly and radially outwardly in the opposite direction.

6. Apparatus according to claim 5 in which said base comprises an upper and a lower portion and means for supporting said upper portion on said lower portion and permitting the relative rotation of said two portions about a generally vertical axis,

together with brake means for preventing relative rotation of said two base portions, said brake means comprising coaxial and oppositely facing annular flanges carried on said base portions and normally having no more than light engagement,

a brake button carried in said upper base portion and movable into and out of frictional and pressureapplying and braking engagement with said flange carried on said lower base portion tending to press said flange carried by said lower base portion into frictional braking engagement with said flange carried by said upper base portion,

camming means mounted on said shaft and engageable with said brake button for urging it into frictional and pressure-applying engagement with said flange carried by said lower base portion upon rotation of said shaft in a direction carrying said tipping and lifting portion in a radially outwardly and axially downwardly direction with respect to said leg element out of cooperating engagement with and beyond said lifting ring when positioned in tipped engagement a limited distance below said locking ring and disengageable from said brake button and releasing it from frictional pressure-applying engagement with said engaged flange upon rotation of said shaft in the opposite direction.

7. Apparatus according to claim 1 in which said rings are provided with internal bores for receiving said leg element and which internal bores have diametrically and axially opposite cylindrical gripping surfaces for gripping engagement with opposite sides of said leg element when said rings are tipped out of their free-passage positions, each of said surfaces being generated about an axis laterally offset from and parallel to the other with the least dimension between said surfaces being greater than the outside diameter of said leg element.

8. Apparatus according to claim 1 together with resil ient means for supplying a biasing force tending to lift said locking ring into its free-passage position with respect to said leg element and tending to lower and slide said lifting ring down and along said leg element and to position said lifting ring in tipped and gripping engagement with said leg element spaced a limited distance below said locking ring as permitted by downward motion of said movable operating means, said resilient means comprising a first spring supplying a force acting downwardly on said side of said lifting ring engageable by said movable operating means and a second spring supplying a force acting downwardly on the substantially opposite side of said lifting ring, said first spring being unstressed and lacking further force after action through a limited distance corresponding to the limited distance of said spacing between said two rings.

References Cited by the Examiner UNITED STATES PATENTS 381,040 4/1888 Stuck 248-410 590,774 9/1897 Rexroth 248410 797,040 8/1905 Adam 248,415 X 836,303 11/1906 Christensen 248410 X FOREIGN PATENTS 426,880 4/1935 Great Britain.

CLAUDE A. LE ROY, Primary Examiner.

JOHN PETO, Examiner. 

1. APPARATUS FOR LIFTING AND LOWERING A LOAD COMPRISING A BASE PORTION, AN EXTENSIBLE AND RETRACTABLE LEG ELEMENT HAVING A GENERALLY VERTICALLY EXTENDING LONGITUDINAL AXIS AND MOUNTED ON AND SUPPORTED BY SAID BASE PORTION FOR EXTENSION AND RETRACTION ALONG ITS SAID LONGITUDINAL AXIS, A LOCKING RING ENCIRCLING SAID LEG ELEMENT AND PIVOTALLY CONNECTED ALONG ONE SIDE TO SAID BASE PORTION FOR SWINGING MOVEMENT ABOUT A GENERALLY HORIZONTAL AXIS, THE INSIDE TRANSVERSE DIMENSIONS OF SAID LOCKING RING BEING LARGE ENOUGH TO PERMIT PASSAGE THERETHROUGH OF SAID LEG ELEMENT WHEN SAID RING SWINGS TO A FREEPASSAGE POSITION PLACING SAID TRANSVERSE DIMENSIONS SUBSTANTIALLY IN A PLANE NORMAL TO SAID LONGITUDINAL AXIS OF SAID LEG ELEMENT AND SMALL ENOUGH TO PREVENT PASSAGE THERETHROUGH OF SAID LEG ELEMENT BY GRIPPING ENGAGEMENT ON OPPOSITE SIDES THEREOF BY ADJACENT PORTIONS OF SAID RING WHEN SAID RING SWINGS AWAY FROM A FREE-PASSAGE POSITION, A LIFTING RING ENCIRCLING SAID LEG ELEMENT BELOW SAID LOCKING RING AND HAVING A LOOSE TIPPING FIT WITH SAID LEG ELEMENT, THE INSIDE TRANSVERSE DIMENSIONS OF SAID LIFTING RING BEING LARGE ENOUGH TO PERMIT PASSAGE THERETHROUGH OF SAID LEG ELEMENT WHEN SAID RING TIPS TO A FREE-PASSAGE POSITION PLACING SAID TRANSVERSE DIMENSIONS IN A PLANE NORMAL TO SAID LONGITUDINAL AXIS OF SAID LEG ELEMENT AND SMALL ENOUGH TO PREVENT PASSAGE THERETHROUGH OF SAID LEG ELEMENT BY GRIPPING ENGAGEMENT ON OPPOSITE SIDES THEREOF BY ADJACENT PORTIONS OF SAID RING WHEN SAID RING TIPS AWAY FROM A FREE-PASSAGE POSITION, MOVABLE OPERATING MEANS SUPPORTED BY SAID BASE PORTION AND COMPRISING A TIPPING AND LIFTING PORTION HAVING AN UP AND DOWN COMPONENT OF MOTION ADJACENT TO AND EXTENDING ALONG SAID LEG ELEMENT, SAID TIPPING AND LIFTING PORTION HAVING COOPERATING ENGAGEMENT WITH THE SIDE OF SAID LIFTING RING GENERALLY VERTICALLY BELOW THE PIVOTALLY CONNECTED SIDE OF SAID LOCKING RING AND MOVABLE UPWARDLY FOR TIPPING SAID LIFTING RING INTO GRIPPING ENGAGEMENT WITH OPPOSITE SIDES OF SAID LEG ELEMENT AND FOR LIFTING SAID LIFTING RING SO TIPPED AND ENGAGED AND THEREBY EXTENDING SAID LEG ELEMENT UPWARDLY AND THROUGH SAID LOCKING RING, SAID MOVABLE OPERATING MEANS HAVING A RANGE OF MOTION OF SUFFICIENT EXTENT WHILE ENGAGED WITH SAID LIFTING RING TO RAISE SAID LIFTING RING TO AN UPPER LIFTED POSITION OF COOPERATING ENGAGEMENT WITH SAID LOCKING RING, SAID TIPPING AND LIFTING PORTION OF SAID MOVABLE OPERATING MEANS HAVING SUPPORTABLE ENGAGEMENT WITH SAID LIFTING RING RADIALLY INWARDLY OF THE HORIZONTAL AXIS OF PIVOTAL MOTION OF SAID LOCKING RING AND SAID BASE FOR URGING TOGETHER AND TIPPING BOTH OF SAID RINGS OUT OF THEIR TIPPED POSITIONS OF GRIPPING ENGAGEMENT INTO THEIR FREE-PASSAGE POSITIONS PERMITTING THE DOWNWARD PASSAGE OF SAID LEG ELEMENT THROUGH BOTH OF SAID RINGS. 